1. Field of the Invention
The present invention relates to a field-effect type thin-film transistor in which a thin film semiconductor and an insulating material are formed on a substrate with a concavoconvex surface, and a method for manufacturing the same.
2. Description of the Related Art
In general, upon manufacturing a thin-film transistor (TFT), an exposing device for transferring a necessary pattern onto a substrate is used. This exposing device is constituted by an exposing optical system for transferring a fine pattern onto a substrate, an alignment system that positions a mask and the substrate with high precision, and an automatic transporting system that automatically transports the mask and the substrate. Prior to an exposing process in which such an exposing device is used, a resist thin film having predetermined photosensitivity is formed on the substrate.
In recent years, with respect to liquid crystal apparatuses, various attempts are being made to achieve high performances of the liquid crystal apparatus by providing high definition in the display accuracy and a low power-consumption driving process. As the performances of the liquid crystal apparatus become higher, the precision of TFT formed on the liquid crystal display has been improved to a sub-micron level (<1 μm), with the result that demands for fine patterning on wide area is increasing.
In order to achieve such fine patterning, an exposing technique which meets the necessary degree of precision is required indispensably, however, an exposing device and an exposing technique with resolution which completely satisfy such a degree of precision have not been completed from the viewpoint of throughputs, and superior techniques need to be developed.
Moreover, the integration of the DRAM that is a typical example of LSI in being improved in a remarkable degree, that is, four times in these three years. Accordingly, the miniaturization of the integrated circuit pattern is being improved, and there are practical needs for line-width processing precision of not more than 130 nm.
Under these circumstances, as an example of a fine-patterning technique generally used as a pattern-forming technique, a photolithography technique (for example, see “Flat Panel Display '91”, Setsuo USUI, published by Nikkei Business Publications, Inc., 1991, p. 117-128) can be listed. As a fine-patterning technique for small quantity, large variety products, a direct-drawing technique and the like using an electron beam can be listed.
However, the above mentioned fine-patterning techniques have respective problems. For example, in the photolithography technique, there is a limitation in the resolution in association with the light wavelength, and the problem that transferring and exposing in a scale of not more than 100 nm are difficult has been pointed out (for example, see Journal of Japan Society of Grinding Engineers, by TANIGUCHI et al., published in 2002 vol. 46, issue 6, p.282-285). Moreover, in the direct drawing technique using an electron beam, it has been recognized that the throughput per unit time is insufficient, and is not suitable for mass production.
On the other hand, “Flat Panel Display '91”, Setsuo USUI, published by Nikkei Business Publications, Inc., 1991, p. 117-128 introduces a nano-imprint lithography technique as a fine-patterning technique capable of climbing out of the limitation of resolution in the above mentioned photolithography technique. This nano-imprint lithography technique is a technique in which: thermoplastic PMMA (polymethylmethacrylate) is provided to a pattern transferring layer on a silicon substrate, and a mold that has been preliminarily patterned is pressed onto the pattern transferring layer so that a fine concavoconvex pattern is formed on the PMMA resin layer. Thereafter, forming of a wiring pattern by forming Al or the like is being studied. Moreover, Japanese Patent Application Laid-Open No. 11-204742 discloses a technique in which a desired concavoconvex pattern is formed by transferring concavoconvex of a stamp by using a 2P (Photo-Polymerized) method, which is a technique similar to the nano-imprint lithography technique.
However, the above mentioned nano-imprint lithography technique and techniques similar thereto are still under development, and have not been fully researched, and in particular, with respect to the field-effect type thin-film transistor and method for manufacturing thereof, there are no examples of the research and practical application.